German Patent Application Nos. DE 100 19 416 A1, DE 100 19 417 A1, and DE 100 19 418 A1 describe general concepts for rollover sensing using methods and devices based on the analysis of a yaw rate sensor and two acceleration sensors which are integrated in the central airbag control unit. The yaw rate sensor ascertains, by the gyroscopic principle, the rotation rate about the longitudinal axis of the vehicle; in addition, the acceleration sensors measure the acceleration of the vehicle in the direction of the transverse and vertical axes of the vehicle. The yaw rate is analyzed in the main algorithm. Using the measured values of the acceleration sensors, the type of rollover may be recognized, and these values are also used for plausibility checking. If the yaw rate algorithm detects a rollover, safety measures are activated only if they are enabled by the plausibility check at the same time.
A timely deployment decision in the event of a rollover at a high lateral acceleration by taking into account a float angle and a transverse velocity of the vehicle, as well as a vehicle tipping motion, is described in German Patent Application No. DE 101 49 112 A1.
However, the float angle and therefrom the lateral velocity as needed for rollover detection are not determinable by conventional methods such as used in vehicle dynamics control, for example, in an angle range greater than 20°. These methods, such as those using a model from tire characteristics and lateral force, for example, are suitable only for angle ranges of less than 10°. The reason for the small validity range is that vehicle dynamics control may no longer be successfully performed at larger float angles.
German Patent Application No. DE 102 39 406 A1 describes a device for determining float angles greater than 20° and the lateral velocity for rollover detection. This device divides the vehicle's state into chronologically consecutive phases and determines the float angle and the vehicle's transverse velocity from the vehicle dynamics data differently in the individual phases. The disadvantage here is that the initial float angle for “setting up” the algorithm is a constant parameter, which is a function of the application and of the vehicle.